Chemical Analysis Flashcards
what is a pure substance?
a substance that is not mixed with any other substance
how do we know a mixture is pure? (2)
both the melting point and boiling point will be specific fixed temperatures
if it melts and boils over a range of temperatures, it is not a pure substance
what is a formulation (2)
- a complex mixture that has been designed as a useful product
- in a formulation, the quantity of each component is carefully measured so that the product has the properties we need
what are some examples of formulations? (5)
fuels
cleaning products
alloys
fertilisers
food
what is paper chromatography?
allows us to separate substances based on their different solubilities
what acts as the stationary phase in paper chromatography?
the paper, because it does not move
what acts as the mobile phase in paper chromatography?
the solvent, because it moves up the paper
in which case would a single spot of ink be the outcome during paper chromatography?
if the original ink is a pure compound
why is the starting line drawn in pencil in paper chromatography?
because if it was drawn in pen, the pen ink would move up the paper with the solvent
how do you calculate RF value?
RF = distance moved by substance divided by distance moved by solvent
what is the test for hydrogen gas? (2)
- insert a burning splint into a test tube that contains the gas
- if hydrogen is present, it will make a pop sound
what is the test for oxygen? (2)
- place a glowing splint into a test tube that contains the gas
- if oxygen is present, the splint will relight
what is the test for carbon dioxide? (2)
- draw some of the gas into a plastic pipette and then bubble it through the limewater
- if carbon dioxide is present, the limewater will turn cloudy
what is the test for chlorine gas? (2)
- insert damp litmus paper into the test tube containing the gas
- if chlorine is present, the litmus paper will be bleached and turn white
